<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div id="app">

    <li v-for="(item,index) in items">
        {{item.message}}==>{{index}}  <!-- index 为数组下标，也可以不要 -->
    </li>

</div>



<script src="https://cdn.jsdelivr.net/npm/vue@2.5.16/dist/vue.js"></script>
<script>
    var app = new Vue({
        el: '#app',
        data: {
            items: [
                {message: 'Java'},
                {message: 'Vue'},
                {message: 'Spring'}
            ]
        }
    });

</script>
</body>
</html>